A novel method for applying nanotechnology to the early detection, localization and potential treatment of ovarian cancer has been developed. Recent measurements, using live ovarian cancer cell lines and the ovarian cancer marker CA-125, have shown that the sensitivity of this method is better than 105 cells at depths of 5 - 8 cm from the sensor. This is significantly more sensitive than the 108 cells required for ultrasound or x-ray imaging. Sensitive biomagnetic sensors are used to measure the remanence fields of superparamagnetic nanoparticles conjugated with specific markers for ovarian cancer cells or pre-cancerous lesions. Measurements indicate that 104 nanoparticles attach to each cancer cell yielding a high magnetic moment/cell. An array of SQUID sensors are used to detect and localize these superparamagnetic nanoparticles. In order to develop protocols for clinical trials, experiments are proposed using nanoparticles, labeled with several ovarian markers, injected into phantom ovaries, ovarian tissue, and extracted human ovaries. Following this, multicomponent nanoparticles, containing both marker and anti-cancer molecules will be investigated for cancer destruction using magnetic concentration. In subsequent clinical applications, labeled-magnetic nanoparticles will be injected into the patient using the procedures developed in these studies.